Paper guide for corona discharge devices and the like



Oct. 4, 1966 Enema ETAL 3,276,773

PAPER GUIDE FOR CORONA DISCHARGE DEVICES AND THE LIKE Filed Oct. 25, 1965 [NVENTORS EM/L 7/6512 525K): 6 (ORA/4v Unitfid S es ar 3,276,773 PAPER GUIDE FOR CORONA DISCHARGE DEVICES AND THE LIKE Emil Tiger, Highland Park, Erskine G. Corman, Forest I Park, and Kenneth R. Reick, Downers Grove, 11]., as-

signors to Formfoto Manufacturing Company, Villa Park, 11]., a corporation of Illinois Filed Oct. 23, 1965, SerrNo. 503,773

12 Claims. (Cl. 27153) This application is a continuation-impart of our application Serial No. 401,626, filed October 5, 1964.

The invention relates to improvements in paper guide means for corona discharge devices and the like and more particularly concerns such means which will guide a forwardly moving paper sheet with substantial accuracy into the nip of feed rollers.

In our aforesaid copending application, an improved corona discharge device for use in applying the electrostatic charge to paper for producing copies electrophotographically is disclosed, including an improved paper guiding structure in the slot or passage through which the paper passes in being charged. Due to warpage or other reason, the leading edge of the paper sheet on leaving the corona discharge device was found sometimes to deviate undesirably from a direct path to the nips of the feed rollers which grip and move the paper sheet onward from the charging zone of the machine.

It is therefore an important object of the present invention to provide improved paper guiding means for directing a paper sheet substantially directly to paper advancing means.

Another object of the invention is to provide on a paper guiding and guard structure in a corona discharge device new and improved exit guide structure for paper sheets undergoing treatment in the device.

A further object of the invention is to provide new and improved guide finger structure on limited contact paper path defining structure. Other objects, features and advantages of the present invention will be readily apparent from the following detailed description of a preferred embodiment thereof taken in conjunction with the accompanying drawings, in which:

FIGURE 1 is a side elevational view of a corona discharge device embodying'features of the invention;

FIGURE 2 is an enlarged cross sectional detail view of the corona discharge device taken substantially on the line -II--l1 of FIGURE 1 and showing the same, schematically, associated with infeed and discharge transport rollers; and

FIGURE 3 is a fragmentary plan view taken substantially on the line III-HI of FIGURE 1.

A corona discharge device embodying features of the invention comprises separably attached, opposed complementary sections -5 and 7 cooperating to define therebetween a corona discharge zone passage 8 of a width, length and depth as desired for copy sheets to be electrostatically charged. Each of the sections 5 and 7 comprises an elongated, hollow, dielectric one-piece body frame 9, desirably rectangular in plan and open at its inner and outer faces, with a metal shielding flange hood plate 10 fitted into the outer 'face and retained at least in part by stud posts 11 at the opposite ends of the flame section. At the opposite sides of the passage 8, the frame 9 has respective bridge flanges 12 having spaced notches 13 within which 'are accommodated corona discharge wires I14 which are strung longitudinally between the bridge flanges and spaced from the passage 8 in traversing relation to the paper path through the passage 8, as is desirable. Suitable electrical connectors 15 on electrical "ice cords 17 are provided on the sections '5 and 7 for connecting the corona wires to a high potential source.

Successive paper sheets P are delivered by a set of driven rollers 18 and 19 into the mouth or receiving end of the passage 8 and through the passage to exit from the discharge end into the nips of a set of driven transport rollers 20 and 21. Guidance for the paper sheet through the passage 8 with minimum contact and to afford full exposure of the opposite surfaces thereof to the corona discharge from the wires 14 is assured by a respective series of integrally connected, longitudinally spaced, transversely diagonally extending strip-like paper guide spacers 21 bridging across passage-recessed edge portions of opposite spaced longitudinal side flange Walls defining the body frames 9. These spacer guides 22 are as thin as practicable with their respective planes normal to the longitudinal axis of the device so as to afford a minimum of corona obstruction while having adequate flange width along such planes for strength. To avoid deflecting the paper sheet from a straight path through the passage 8, the spacer guides 22 are provided in two oppositely diagonal'groups in each set, located each way from the longitudinal center. The diagonal relationship of the groups of spacer guides 22 on the respective opposite body frames 9 are arranged in complementary relation so that they align with one another, mirror fashion. At their opposite ends, the spacer guides 22 are connected as ribs integrally in one piece with the iframe side walls. For limiting paper contact, the spacer guides 22 are constructed in arched form, at least on the sheet guiding edges thereof to provide convex longitudinal respective edges 23.

To provide :a reasonably broad gap entry into the passageway 8, the guide edges 23 merge with relatively flaring lead-in edges 24 provided on the respective side walls of the frame members 9 at the entry end of the passageway.

According to the present invention, means are provided for guiding the leading ends of successive paper sheets, as they pass from the discharge end of the passageway 8, substantially straight into the nips of the transport rollers 20 and 21. To this end, the guide edges 23 are reversely curved adjacent to the discharge end of the passageway to provide relatively large rad-ins lead-out guide surface portions 25 converging toward one another on the respectively opposed spacer guide ribs or bars. At their outermost ends, the reversely curved guide surface portions 25 terminate in respective guide fingers 27 which project toward one another on the opposed bars 22 in narrow gap exit spaced relation as integral parts of the respective spacer guide bars. The spacing between the opposed complementary guide fingers 2-7 is desirably only slightly greater than the thickest sheets expected to be passed through the passage.

As will be apparent, should the leading end of a sheet be biased for any reason from a centered plane relationship as it is projected through the passageway 8 defined by the paper guiding grid of guide bar ribs 22, such leading end will be gently gradually diverted toward said plane as it approaches the exit gap, and as it leaves this gap will be oriented by the limited contact guide fingers 27 substantially straight toward the nips of the rollers 20 and 21.

It will be understood that modifications and variations may be effected without departing trom the scope of the novel concepts of the present invention.

We claim as our invention:

1. A corona discharge device comprising:

opposed dielectric body frames defining a passageway therebetween affording a path for paper to be electrostatically charged;

corona discharge wires strung on said body' frames across said passageway;

spaced apart integral dielectric spacer and paper guide ribs on said frames interposed between said wires and said path and defining a relatively broad entry gap into said passageway; and

a guide finger projections on said ribs at the exit end of said passageway defining a relatively narrow discharge gap.

2. A device as defined in claim 1, in which said ribs have throughout the major extent of their length from said entry gap to said fingers convexly arched guide edges and said edges terminating in reversely curved lead-out edge portions terminating on said fingers.

3. In combination in electrostatic paper charging apparatus:

a set of delivery rollers;

a set of transport rollers in spaced alignment with the delivery rollers;

a corona discharge device located between said sets of rollers and defining a charging passageway through which paper to be charged is projected by the delivery rollers toward said transport rollers; means defining a substantially broad gap entry into said passageway; and

means defining a relatively. narrow exit gap aligned with the nips of the transport rollers and having convergently related lead-out edges joining said exit gap means.

4. A corona discharge device comprising: 7

opposed assemblies defining there'between a path for paper to be electrostatically charged and having corona discharge wires extending in spaced relation across said path;

dielectric paper guide and spacer means on opposite sides of said path and including spaced apart spacer rib means between the discharge wires and the path, said guide and spacer means defining an entry at one end of said path and an exit at the opposite end of said path; and

guide finger means on said rib means located at said exit for orienting the leading edge of paper toward the predetermined position beyond the device such as paper transporting means.

5. A corona discharge device of the character described comprising:

a molded plastic hollow body frame including longitudinally extending spaced walls arranged to extend across a path for paper to be electrostatically charged;

integral paper spacer guide ribs molded at opposite ends to the respective walls and adapted to oppose paper sheets moving in said path; and

integral paper guide finger projections on one of the ends of said ribs.

6. A device as defined in claim 5, in which said ribs are substantially wider in planes intersecting side walls and presenting narrow guide edges to said path.

7. A device as defined in claim 6, in which said edges are arched toward said path except adjacent to said finger projections and merge on reversely curved lead-out edges to the tips of said finger projections.

8. A paper guide device of the character described comprising:

supporting structure;

a plurality of spaced apart substantially coextensive spacer guide ribs having guide edges aligned to define a paper guide;

said ribs having at one of the ends thereof guide finger projections extending beyond said edges.

9. A device as defined in claim 8, in which said edges are of convexly arched form throughout their major extent and have reversely extending lead-out portions adjacent to and running onto said projections.

10. A device as claimed in claim 8, in which said edges have portions thereof extending angularly to the tips of said fingers for biasing leading edges of said paper sheets toward the tips of said project-ions.

11. In a paper guiding device of the character descri'bed:

an elongated supporting structure adapted to extend across a path of movement for paper sheets;

a paper guiding grid supported by said structure comprising substantially spaced bars extending in the general direction of paper movement of said path and having paper delivery ends and paper exit ends; and

paper guide finger projections at the exit ends of said bars.

12. A device as defined in claim 11, in which said sup porting structure and said bars and finger projections are all molded integrally in a one-piece unit.

References Cited by the Examiner UNITED STATES PATENTS 2,220,264 11/ 1940 Morrison 27 15 3 2,486,985 11/ 1949 Ruderfer.

2,922,883 1/1960 Giaimo 25049.5 2,965,481 12/1960 Gu-ndlach 250-495 3,075,078 1/1963 Olden 250-49.5 3,088,386 5/1963 Sugarman 1.7

M. HENSON WOOD,.JR., Primary Examiner.

J. N. ERLICH, Assistant Examiner. 

1. A CORONA DISCHARGE DEVICE COMPRISING: OPPOSED DIELECTRIC BODY FRAMES DEFINING A PASSAGEWAY THEREBETWEEN AFFORDING A PATH FOR PAPER TO BE ELECTROSTATICALLY CHARGED; CORONA DISCHARGE WIRES STRUNG ON SAID BODY FRAMES ACROSS SAID PASSAGEWAY; SPACED APART INTEGRAL DIELECTRIC SPACER AND PAPER GUIDE RIBS ON SAID FRAMES INTERPOSED BETWEEN SAID WIRES AND SAID PATH AND DEFINING A RELATIVELY BROAD ENTRY GAP INTO SAID PASSAGEWAY; AND GUIDE FINGER PROJECTIONS ON SAID RIBS AT THE EXIT END OF SAID PASSAGEWAY DEFINING A RELATIVELY NARROW DISCHARGE GAP. 